1. Technical Field
The present invention relates to an optical transceiver module and, more particularly, to an optical transceiver module which integrates a fiber-optic lens element and an optical transceiver sub-module and has a z-axis positioning base for increasing the lateral fixing force between the optical transceiver sub-module and a substrate.
2. Description of Related Art
Fiber-optic communication is a technique whereby signals are transmitted in the form of light waves from a signal transmitting port to a signal receiving port after conversion from and before conversion back to electrical signals. To convert an electrical signal into an optical signal or vice versa, an optical transceiver module is provided at each end of a fiber-optic. Each optical transceiver module includes an optical transmitter sub-module for converting an electrical signal into an optical signal and transmitting the optical signal and an optical receiver sub-module for receiving the optical signal and converting it into an electrical signal. A typical optical transmission element for use in fiber-optic communication is the laser diode, which is a coherent light source with relatively high directivity and whose coupling efficiency with a single-mode optical fiber can be as high as 50%. The relatively narrow laser output spectrum also helps increasing transfer rate and reducing modal dispersion. The optical receiving element, on the other hand, is usually a photodiode, such as a p-n junction diode, a p-i-n diode or an avalanche photodiode, which converts a received optical signal into an electrical signal through the photoelectric effect.
Conventionally, the optical transmitter sub-module and the optical receiver sub-module are provided on a printed circuit board and are connected to the printed circuit board via a light turning device which is configured for optically coupling an optical signal to an optical fiber. During assembly, the light turning device must be aligned with the optical transmitter sub-module and the optical receiver sub-module respectively, and the alignment process requires an optical calibration instrument for respectively and precisely aligning the plural lenses on the light turning device with the optical transmission element and the optical receiving element. However, as the optical calibration instrument required is very expensive, and assembly plants generally do not have the necessary technique for calibrating the light turning device, difficulties in mass production and progressive assembly tend to arise. Moreover, due to the fact that the copper foils on a rigid printed circuit board cannot be densely arranged, the finished product is bulky and occupies a lot of space. If, in order to increase copper foil density, a flexible printed circuit board is used instead as the circuit substrate, the properties of the flexible printed circuit board will result in an insufficient fixing force between the circuit board and the optical receiving element provided thereon such that, after repeated insertion and removal of an optical fiber connecter, the optical receiving element is very likely to get loose or even come off the flexible printed circuit board as a result of the lateral forces generated by the insertion and removal operations. Should that happen, the optical transceiver sub-module on the flexible printed circuit board will be shifted in position, making the optical transmission element and the optical receiving element out of focus of the lenses and thus lowering the yield rate.